The invention relates to a method and an arrangement for removing the slag incrustations as well as possibly also the inner marginal layers infiltrated by metal or metal oxides, on the refractory inner lining, particularly ceramic lining, of melting or casting vessels which are at least internally cylindrical over the substantial part of their length.
During the operative use of such vessels, slag deposits on the internal walls of the lining which come into contact with the molten material. Not only can these slag incrustations become so thick that they considerably reduce the volumetric capacity of the vessels, but also they cause, and especially in induction heated vessels, a considerable reduction in the melting output so that the manufacturing operation is sensibly interfered with. Therefore, it is necessary to remove these slag incrustations from time to time.
These operations are performed predominantly manually, using special tools and requiring heavy physical exertion on the part of the operating personnel. Herein, such operations are preferably carried out with the vessel in hot condition inasmuch as the slag incrustations can be more readily removed under these conditions. However, the worker discomfort due to the heat is very great when resort is had to this operating procedure. While it is true that the removal of the incrustations is more difficult in the cold state of the vessels, the discomfort resulting from the heat which is radiated from the vessel interior is avoided under these conditions. Whether operations are carried out in the cold or in the hot condition of the vessel, however, the wear of the cleaning tools which have been heretofore used for this purpose is very high.
It would be conceivable to perform the removal of the slag incrustations mechanically by drilling or boring as it is known, for instance, for the renewal of the refractory lining in melting vessels. However, even disregarding the fact that the wear of the drilling tools is very high even here because of the extremely hard and brittle slag incrustations, a special problem exists here which resides in the fact that the slag incrustations or deposits do not have any uniform thickness, but rather that this thickness considerably varies both in the circumferential direction of the vessels as well as over their internal height. When it is desired not to run the danger that the drilling tools which, for the most part, also consist of a brittle material, would break due to too high impact stressing, it is necessary, in a very expensive and time-consuming manner, to begin with the smallest possible boring radius and to gradually increase the same in the course of several passes.
Because of the high machinery, time or labor expenditure and the high susceptibility of the boring apparatus to malfunction, which are encountered when the above approach is taken, all attempts to remove the slag incrustations in this manner have failed in the practice so that it remained by the, however also laborious, manual removal of the slag incrustations by means of special tools.
On top of this, what is common to both of these methods is that the danger exists to a high degree that, during the removal of the slag incrustations as well as the possible erosion of the inner marginal layers of the ceramic inner lining which have been infiltrated by metal or metallic oxides, even the unused lining material as well as, under certain circumstances, even the vessel masonry itself, are damaged.